Emergency units, such as exit signs and light fixtures, are commonly used in public buildings to indicate and illuminate areas such as stairs and exits in the event of a power failure. These fixtures typically have an emergency backup power system such as a battery that automatically turns on the emergency light when the primary power source is interrupted.
Once an emergency unit is installed, it must be serviced periodically to make sure it is functioning properly. Service issues can range, for example, from a simple battery replacement to the replacement of a complex, high-voltage circuit board. While some units have the ability to alert the user of an error or malfunction in the unit, determining the exact cause can be time consuming and expensive.